Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 41: Focus Session: Functional Molecules at Surfaces II

O 41.5: Invited Talk

Tuesday, March 17, 2020, 11:45–12:15, TRE Ma

Molecular Nanoprobe - utilizing a single molecule as detector — •Markus Leisegang — Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

The transport properties of electrically conducting materials are determined by charge carriers scattering at electrons, phonons, and defects. A fundamental understanding of the underlying processes will require experiments on the level of single defects, bringing along the necessity of resolving transport properties down to the nanometer or even atomic scale. One approach towards this goal has been the development of multi-probe STMs, but their minimal tip–tip distance is usually limited to > 30 nm [1]. To circumvent this limitation, we invented the molecular nanoprobe (MONA) technique [2]. In MONA we utilize a charge-induced switching between discrete states of a single surface-adsorbed molecule, e.g. a tautomerization process, to detect the current injected remotely by the STM tip. Due to the local, near-field charge injection mechanism and the small size of the detector molecule, MONA allows for transport measurements in atomically controlled environments and over distances of a few nanometers. Our investigations on Ag(111) with its electron-like surface state show how scattering and interference processes affect the atomic-scale transport. Furthermore, we reveal the influence of the atomic lattice on transport properties in anisotropic surfaces.
[1] S. Yoshimoto et al., Nano Lett. 7, 956-959 (2007).
[2] M. Leisegang et al., Nano Lett. 18, 2165-2171 (2018).